Before: Save g:ale_python_yapf_executable " Use an invalid global executable, so we don't match it. let g:ale_python_yapf_executable = 'xxxinvalid' call ale#test#SetDirectory('/testplugin/test/fixers') let b:bin_dir = has('win32') ? 'Scripts' : 'bin' After: Restore unlet! b:bin_dir call ale#test#RestoreDirectory() Execute(The yapf should include the .style.yapf file if present): call ale#test#SetFilename('../test-files/python/with_virtualenv/dir_with_yapf_config/foo/bar.py') AssertEqual \ { \ 'command': \ ale#Escape(ale#path#Simplify(g:dir . '/../test-files/python/with_virtualenv/env/' . b:bin_dir . '/yapf')) \ . ' --no-local-style' \ . ' --style ' . ale#Escape(ale#path#Simplify(g:dir . '/../test-files/python/with_virtualenv/dir_with_yapf_config/.style.yapf')), \ }, \ ale#fixers#yapf#Fix(bufnr('')) Execute(pipenv is detected when python_yapf_auto_pipenv is set): let g:ale_python_yapf_auto_pipenv = 1 call ale#test#SetFilename('../test-files/python/pipenv/whatever.py') AssertEqual \ { \ 'command': ale#Escape('pipenv') . ' run yapf', \ }, \ ale#fixers#yapf#Fix(bufnr('')) Execute(Poetry is detected when python_yapf_auto_poetry is set): let g:ale_python_yapf_auto_poetry = 1 call ale#test#SetFilename('../test-files/python/poetry/whatever.py') AssertEqual \ { \ 'command': ale#Escape('poetry') . ' run yapf', \ }, \ ale#fixers#yapf#Fix(bufnr('')) Execute(uv is detected when python_yapf_auto_uv is set): let g:ale_python_yapf_auto_uv = 1 call ale#test#SetFilename('../test-files/python/uv/whatever.py') AssertEqual \ { \ 'command': ale#Escape('uv') . ' run yapf', \ }, \ ale#fixers#yapf#Fix(bufnr(''))